Deposition Study of Bi_2Te_3 Thin Films by Close-Spaced Vapor Transport and Close-Spaced Sublimation

摘要

We have successfully used the Close-Spaced Sublimation technique to grow Bi_2Te_3 thin films with god crystallinity and composition under optimal conditions. Some unsuccessful attempts have also been made with the close-Spaced Vapor Transport technique. A study of the deposition reactions of Bi_2Te_3 thin films occurring in these closed-spaced techniques, using Bi_2Te_3 pellets or powder as the source material and iodine as the transport reagent have been conducted. Based on the study of the thermodynamic properties of Bi_2Te_3 and of the iodide compounds involved in the process as well as the experimental conditions, different reversible reactions have been considered to explain the final composition of the thin films obtained. Films grown with various operational parameters (source temperature T_(so), substrate temperature T_(su), distance between source and substrate 1 and time of deposition t) have been characterized by X-ray diffraction, energy dispersive X-ray analysis and electron microscopy investigation.